That poster might still have used the Tolkien quote. The existence of the poster does not disprove the attribution, but may in fact support it.

I found a post on the Help.com website which claims, "It has been confirmed by Lord of the Rings Blu Ray Extended Edition Extra Features that this is indeed a J.R.R Tolkein quote." I don't think it depends on the Blu-ray edition, but on any edition that contains the "extra features." So the next step would be to confirm the attribution on the disks, then confirm where *they* got the attribution.